When a semiconductor device where a semiconductor element is mounted on a wiring board is installed and used in an electronic device, due to electromagnetic waves radiated from the semiconductor element, an error in operation of an electric circuit or an electronic component situated in the vicinity of the semiconductor element may be caused or bad influence on a human body may happen. In particular, digitization has progressed in recent electronic devices so that signal sources handle pulse signals. Therefore, a high frequency element of the pulse signal may easily become a noise source. In addition, as high frequency or high speed of signals progresses, influence thereof also progresses.
On the other hand, the semiconductor element may be influenced by electromagnetic waves generated in neighboring electronic components and/or electric circuits or an external atmosphere.
Because of this, it is required to electromagnetically shield the semiconductor element from the surrounding atmosphere. For example, a structure illustrated in FIG. 1 has been suggested.
Referring to FIG. 1, a semiconductor device 10 is a so-called BGA (Ball Grid Array) type semiconductor device. A semiconductor element 3 is mounted and fixed on a wiring board 2 via a die bonding material not illustrated in FIG. 1 such as a die bonding film. Plural spherical-shaped bumps 1 for outside connection are provided on a lower surface of the wiring board 2. An electrode (not illustrated in FIG. 1) of the semiconductor element 3 is connected to an electrode (not illustrated in FIG. 1) of the wiring board 2 via a bonding wire 4. In addition, the semiconductor element 3, the bonding wire 4, and others are sealed by sealing resin 5.
The semiconductor device 10 is mounted on a wiring circuit board (mother board) 11 via solder or the like so as to be connected to a wiring part of the wiring circuit board 11. For example, the spherical-shaped bumps 1 (two spherical-shaped bumps 1 in the example illustrated in FIG. 1) provided on the lower surface of the wiring board 2 and connected to a ground conductive layer 12 in the wiring board 2 are connected to a ground wiring pattern 13 of the wiring circuit board 11.
Under this structure, it is necessary to block the electromagnetic waves emitted from the semiconductor element 1 from going outside and prevent influence of the electromagnetic waves from the outside atmosphere. However, the structure of the semiconductor device 10 does not have a shielding effect against the electromagnetic waves.
Because of this, a large size metal shielding member 14 is provided on the wiring circuit board 11 so as to cover a surface of the wiring circuit board including a portion where the semiconductor device 10 is provided. A cross section of the shielding member 14 has a configuration of a rectangle lacking one side. The shielding member 14 is connected to electrodes 15 provided on the upper surface of the wiring circuit board 11 via solder. The electrodes 15 are connected to the ground wiring pattern 13 of the wiring circuit board 11.
A process of attaching the shielding member 14 on the wiring circuit board 11 is performed after the semiconductor device 10 is mounted on the wiring circuit board 11.
In addition, in order to improve the efficiency of operations and reduce the number of the shielding members 14, the following example is applied. That is, after plural semiconductor devices 10 are mounted on the wiring circuit board 11, a shielding member is provided on the wiring circuit board 11 so as to shield plural semiconductor devices 10 in a lump.
A high-frequency module component including a resin coating member which has a conduction hole reaching a terminal electrode having ground potential of an electronic component, and a shield metal film which covers the resin coating material has been suggested in Japanese Laid-Open Patent Application Publication No. 2001-244688. In addition, a semiconductor device where a plate is connected to a rear face of a semiconductor substrate having an element electrode on a main face has been suggested in Japanese Laid-Open Patent Application Publication No. 2001-7252. A semiconductor element package where a shield metal layer for electromagnetic shielding is provided on a surface opposite to a lead pattern forming surface of a substrate has been suggested in Japanese Laid-Open Patent Application Publication No. 3-120746.
However, in the structure illustrated in FIG. 1, it is necessary to secure a connecting and fixing area of the shielding member 14 on the wiring circuit board 11. Here, the connecting and fixing area of the shielding member 14 is where the electrodes 15 connected to end parts of the shielding member 14 via the solder are provided. Accordingly, it is difficult to make the size of the wiring circuit board 11 small and to make the size of the electronic device 10 having the wiring circuit board 11 small.
In addition, a process of covering the semiconductor device 10 mounted on the wiring circuit board 11 with the shielding member 14 is performed after the semiconductor device 10 is mounted on the wiring circuit board 11. Therefore, the assembling process is complex.
Furthermore, in a structure where plural semiconductor devices 10 are mounted on the wiring circuit board 11 and the semiconductor devices 10 are shielded in a lump by the shielding member, mutual influence of the electromagnetic waves may occur among the semiconductor devices 10 covered by the shielding member 14 so that errors in operations may happen.